Inspiration
I spent many years as a skinny guy stuck at the same weight. Recently, I have been able to overcome that with certain systems I implemented in my life. Muscle Mass is the collection of these basic systems in one place that create an overall hub for your bulk.
What it does
- sets calorie + protein targets
- logs daily weight + meals (text input)
- gives AI feedback once per day
- tracks weight trend over time
- adjusts targets weekly
How we built it
- React frontend on Replit
- PostgreSQL database for all user data (synced across devices)
- Clerk for user authentication (email + Google sign-in)
- Simple nutrition formulas (Mifflin-St Jeor)
- Gemini AI for daily coaching feedback
- Stripe Checkout for $1.99 one-time Pro upgrade
- Stripe webhook for reliable payment verification
- Express API server sitting between the frontend and the database
Challenges we ran into
Controlling feature creep, simplifying nutrition logic, tuning concise AI responses, enforcing one log per day, and making the UI feel like a real product were the main challenges.
Accomplishments that we're proud of
A fully functional product with a real payment flow, a clear daily feedback loop, and a clean, focused interface was built in under 24 hours.
What we learned
Simplicity drives engagement, most users dislike calorie tracking, feedback loops matter more than precision, AI works best when constrained, and speed outweighs perfection early on.
What's next for Muscle Mass
Next steps include adding user accounts, implementing secure payment validation, improving weekly adjustments, introducing habit tracking, and iterating based on real user feedback.
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